Can't compile using il2cpp in Unity

[Former user]

It seems the IL patching causes il2cpp to crash when compiling for Android in Unity with no additional information. Any ideas as to the problem?

[Nicholas Woodfield]

I don't use Unity, we've had plenty of users of Unity use it...although I don't know if those projects are using il2cpp. The managed library has been updated to target .net standard 1.3 and uses a slightly different IL weaving strategy. If you're still monitoring this issue, you may want to give it a try.

It could also be that il2cpp just isn't compatible with what we're doing.

[Nicholas Woodfield]

Fyi, I'm seeing an error with the latest build when using IL2CPP. One of the MemoryHelper::Read methods. Exception from IL2CPP is a not implemented exception, so it might very well be a bug on their end. It'll require deeper digging.

[Meshal Marakkar]

Has there been any update on this?

[Nicholas Woodfield]

Sorry, no. Haven't had the time to investigate further.

[Nicholas Woodfield]

I've submitted a bug report to Unity regarding this. I think I've narrowed it down to MemoryHelper methods that make use of the 'cpobj' IL instruction. The methods that would be affected are:

• MemoryHelper::Read<T>(IntPtr, out T)
• MemoryHelper::Write<T>(IntPtr, in T)

'cpobj' is used in the singular copy operations where as 'cpblk' is used in the array operations. I see the same build problem if I reference the library SharpDX in my test unity project (many of my interop methods are based on theirs).

The read method can be replaced by the non-out version, which uses 'ldobj' to do the copy (it probably will be inlined in released code anyways) - it only is used in one other place in the code. But the write method doesn't have a substitute and is used in a lot of places.

The only viable way to fix this would be to make a change in my ILPatcher (which is a separate project), and use cpblk instead of cpobj. I am not sure of the performance implications, although ideally I'd rather see this fixed in Unity's IL2CPP backend.

[Meshal Marakkar]

Oh okay. Thank you for following up on this. Looking forward to the fix.

[Denver Coulson]

Have you heard anything from your submitted bug report? We are likewise running into this trying to figure out whether we should try resolving ourselves.

[Nicholas Woodfield]

FYI,

I'm kind of shocked it took this long, but today I got a response from their QA team acknowledging the issue and it's been sent for resolution to their development team.

[Drago Rosson]

Is there any update to this issue?

@nickbenton Is there an issue in https://issuetracker.unity3d.com/ for this?

[Nicholas Woodfield]

They decided not to fix it in IL2CPP.

I’ve updated my ILPatcher to not use the ‘cpobj’ instruction. I did some light testing with IL2CPP and it seems like it’s okay now. The 5.0.0-beta1 nuget package is out so you can give it a try.

[Hamid Younesy]

Hello@Nicholas Woodfield , Could you please elaborate more on your solution? How did you update ILPatcher not to use cpobj insturction?

On OSX, I can build a standalone Unity app with 4.1.0, if I use Mono, but I get the following build error if I use IL2CPP :

Il2cppBuildCache/macOS/x64/il2cppOutput/GenericMethods6.cpp:47380:8: error: no viable overloaded '='
*L_0 = *L_2;
~~~~ ^ ~~~~

Also, I tried the 5.0.0-beta1, and it doesn’t seem to work even with Mono or in Unity Editor. I get the following runtime exception (Editor, OSX):

System.NullReferenceException: Object reference not set to an instance of an object
  at System.Buffer.memcpy4 (System.Byte* dest, System.Byte* src, System.Int32 size) [0x0000e] in <9577ac7a62ef43179789031239ba8798>:0 
  at System.Buffer.Memcpy (System.Byte* dest, System.Byte* src, System.Int32 size) [0x00073] in <9577ac7a62ef43179789031239ba8798>:0 
  at System.String.memcpy (System.Byte* dest, System.Byte* src, System.Int32 size) [0x00000] in <9577ac7a62ef43179789031239ba8798>:0 
  at Assimp.MemoryHelper.Read[T] (System.IntPtr pSrc, T[] data, System.Int32 startIndexInArray, System.Int32 count) [0x00008] in <d40f2b0ad6814d4c8094142d8473733f>:0 
  at Assimp.Unmanaged.AiString.GetString (Assimp.Unmanaged.AiString& aiStr) [0x0002d] in <d40f2b0ad6814d4c8094142d8473733f>:0 
  at Assimp.Mesh.Assimp.IMarshalable<Assimp.Mesh,Assimp.Unmanaged.AiMesh>.FromNative (Assimp.Unmanaged.AiMesh& nativeValue) [0x0000d] in <d40f2b0ad6814d4c8094142d8473733f>:0 
  at Assimp.MemoryHelper.FromNativeArray[Managed,Native] (System.IntPtr nativeArray, System.Int32 length, System.Boolean arrayOfPointers) [0x0006d] in <d40f2b0ad6814d4c8094142d8473733f>:0 
  at Assimp.Scene.Assimp.IMarshalable<Assimp.Scene,Assimp.Unmanaged.AiScene>.FromNative (Assimp.Unmanaged.AiScene& nativeValue) [0x00088] in <d40f2b0ad6814d4c8094142d8473733f>:0 
  at Assimp.MemoryHelper.FromNativePointer[Managed,Native] (System.IntPtr ptr) [0x0003b] in <d40f2b0ad6814d4c8094142d8473733f>:0 
  at Assimp.Scene.FromUnmanagedScene (System.IntPtr scenePtr) [0x0000f] in <d40f2b0ad6814d4c8094142d8473733f>:0 
  at Assimp.AssimpContext.ImportFile (System.String file, Assimp.PostProcessSteps postProcessFlags) [0x0009d] in <d40f2b0ad6814d4c8094142d8473733f>:0 
  at Assimp.AssimpContext.ImportFile (System.String file) [0x00000] in <d40f2b0ad6814d4c8094142d8473733f>:0 

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